1. Field of the Invention
The present invention relates to an image processing device, an imaging device, a computer-readable storage medium, and an image processing method and particularly relates to an image processing device, an imaging device, a computer-readable storage medium, and an image processing method for processing a fluorescent light image based on the fluorescent light from an object.
2. Description of the Related Art
Endoscopes are used in the medical field to observe the internal organs of a subject. An elongated and flexible insertion unit of an endoscope is inserted into the body cavity of a subject, such as a patient. White light is applied to body tissue in the body cavity via the inserted flexible insertion unit. By receiving the light reflected from the body tissue with an imaging unit in the flexible insertion unit, a white light image of the body tissue is captured. The white light image of the body tissue is displayed on a display unit of the endoscope. A user, such as a doctor, observes the interior of the body cavity of the subject using the white light image of the body tissue that is displayed on the display unit of the endoscope.
In the field of endoscopy, endoscopes have also been used recently that allow fluorescence observation of an observed region, such as body tissue, in the body cavity. A fluorescence-observation endoscope applies excitation light to body tissue in the body cavity via a flexible insertion unit that is inserted into the body cavity. The endoscope captures a fluorescent light image of the body tissue by receiving, with its imaging unit in the flexible insertion unit, light of autofluorescence or drug fluorescence that is generated from the body tissue due to the application of excitation light. A user, such as a doctor, visually checks the fluorescent light image of the body tissue, which is captured as described above, using the display unit of the endoscope, and performs fluorescence observation of the observed region using the fluorescent light image of the body tissue. There are also apparatuses that acquire a normalization image based on light emitted from an observed region, such as body tissue, due to the application of light on the observed region, and that performs division regarding a fluorescent light image of the observed region using the normalization image in order to generate a normalized fluorescent light image (see, Japanese Laid-open Patent Publication No. 2002-336187).
In the conventional fluorescence observation, when the luminance of a fluorescent light image of an observed region, such as body tissue, is corrected by a normalization process, a white light image of the observed region is generally used as the normalization image and the luminance value of the fluorescent light image of the observed region is divided by the luminance value of the white light image.